Enter the radius

unit(s) squared

Rectangle

Enter the length of one side
Enter the height of one side

unit(s) squared

Sphere

Enter the radius

unit(s) squared

Square

Enter the length of one side

unit(s) squared

Triangle

Enter the length of the base
Enter the height

unit(s) squared

Now back home.
Or back to extra's.
Or even back to Maths.